Abstract: An upright support structure comprises a telescopic post having a number of longitudinally extending grooves circumferentially distributed on the periphery thereof for clamping engagement with support brackets having respective pairs of commonly operable groove engaging members. Each bracket is adapted to support a variety of accessories in one of different available orientations. A locking device is operatively associated with the telescopic post to provide for incremental adjustment of the length thereof. This is useful when it is desired to securely mount the telescopic post between a floor and a ceiling structure. The post can also be mounted on a mobile base or, alternatively, pivotally mounted between a stationary base and an overhead fixture. Finally, the telescopic post is provided with an internal guiding structure to ensure proper alignment of the post segments forming part of the telescopic post.